1. Technical Field
The present invention relates to a liquid ejecting head such as an ink jet recording head and a liquid ejecting apparatus equipped with the liquid ejecting head, particularly to a liquid ejecting head including a liquid passage through a liquid conducting path, a common liquid chamber, an individual supply path, and a pressure chamber, to a nozzle, and a liquid ejecting apparatus equipped therewith.
2. Related Art
A liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid as a liquid droplet and ejects various kinds of liquid from the liquid ejecting head. Image recording apparatuses such as ink jet recording apparatuses (printers) which include an ink jet recording head (hereinafter, referred to as a recording head) and perform recording by ejecting liquid ink as an ink droplet from the recording head, are typical examples of the liquid ejecting apparatus. Recently, the liquid ejecting head has been used not only for such image recording apparatuses but also for manufacturing a color filter of a liquid crystal display panel, an organic EL element, a thin-film transistor, or the like.
The recording head, a type of the liquid ejecting head, includes a nozzle group (nozzle row) formed of a plurality of nozzles for each type of ink (color or the like), and each nozzle communicates with its corresponding pressure chamber. The recording head further includes a common liquid chamber (also called a reservoir or manifold) to which ink to be distributed to a plurality of pressure chambers is supplied. The common liquid chamber extends in a direction of the pressure chambers being arranged when viewed from above and has a space with a predetermined width (width in a direction perpendicular to the pressure chamber arrangement direction) and depth. In a typical common liquid chamber, a conducting opening which serves as a connection port to the liquid conducting path is positioned at the central portion in the pressure chamber arrangement direction. The ink from a liquid supply source such as an ink cartridge is supplied to the common liquid chamber through the liquid conducting path, from which the ink is distributed to each pressure chamber through the individual supply path. Then, a pressure generation unit such as a piezoelectric device is driven so as to generate pressure fluctuation in the ink in the pressure chamber. This pressure fluctuation causes the ink to be ejected from the nozzle (see JP-A-2003-063010, for example).
The recording head including the aforementioned common liquid chamber has a risk that when air bubbles come into a passage of ink, the air bubbles may cause instability of ink ejection such as a decrease in ejection speed and quantity of the ink ejected from the nozzle, and the like because those air bubbles absorb the pressure fluctuation at the time of ink ejection. Therefore, the structure of the liquid conducting path and the shape of the common liquid chamber are taken into consideration in designing the recording head so as to exclude air bubbles effectively. For example, with regard to a planar shape of the common liquid chamber, either edge of the chamber is tapered, i.e., the width of the chamber in a direction perpendicular to the pressure chamber arrangement direction is gradually reduced toward the edge in the pressure chamber arrangement direction of the common liquid chamber so that the air bubbles do not stagnate at either edge portion of the common liquid chamber.
FIG. 6 is a plan view illustrating an example of a configuration of a common liquid chamber and its surroundings in related art. In the common liquid chamber in the related art, ink supplied from a conducting opening 52 flows toward an edge portion in the pressure chamber arrangement direction as indicated by streamlines A and B. Such configuration in the related art has the following problems. That is, in a common liquid chamber 51, for example, in the case where an air bubble X covers an individual supply path 54 which communicates with a pressure chamber 53, there exists a risk that the ink ejection from a nozzle 55 corresponding to the pressure chamber 53 becomes unstable. Further, if the air bubble X flows along the ink streamline A from the conducting opening 52 toward the edge of the common liquid chamber 51 and moves to an individual supply path communicating with another pressure chamber, the ink ejection from a nozzle corresponding to this pressure chamber will become unstable. That is, there exists a problem in which the instability of ink ejection propagates with the movement of the air bubble. In addition, there exists another risk that ink ejection at a pressure chamber located in a position far from the conducting opening 52, i.e., a pressure chamber located in the edge portion in the pressure chamber arrangement direction, becomes unstable in comparison with that at a pressure chamber near the conducting opening 52 due to a pressure loss which is generated during the process of flowing from the conducting opening.